This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-296641 filed on Sep. 28, 2000.
1. Field of the Invention:
The present invention relates to a driving apparatus having a plurality of driving means suitable for use in an air conditioner for a vehicle.
2. Description of Related Art:
A conventional driving apparatus drives a member is driven by an electric motor, and the position of the driven member is detected by a potentiometer (position detecting means).
For example, an air conditioner for a vehicle has an air inlet door for switching an air to be introduced between the inside air and the outside air, a temperature adjusting door for adjusting the temperature of blown air, a mode door for switching the direction of blowing air into a vehicle compartment, and the like. A driving apparatus of the air conditioner directly detects the position of each door (driven member) by a potentiometer provided for the door.
However, in the driving apparatus, to detect the positions of the driven members, potentiometers of the same number as that of the driven members are necessary. This is one of factors of the high cost of the driving apparatus.
An object of the present invention is to reduce the cost of a driving apparatus having a plurality of driven members, by enabling the positions of the driven members to be detected by a single position detecting means.
According to the present invention, there is provided a driving apparatus including electric motors, a plurality of driven members driven by the electric motors, a control means for controlling operation of the electric motors, and a position detecting means for detecting a rotation position of each of the electric motors. When a request of simultaneously operating the plurality of driven members is made, the control means controls the electric motors so as to sequentially operate the driven members one by one.
Thus, the rotation positions of the electric motors can be detected by the single position detecting means. The positions of the driven members are detected (estimated) based on the detection results, thereby eliminating potentiometers provided for the conventional driving members.
Here, when a plurality of driven members are simultaneously operated, the position of each of the driven members cannot be detected by the single position detecting means.
Thus, according to the present invention, when a request of simultaneously operating the plurality of driven members is made, by sequentially operating the driven members one by one, the positions of the plurality of driven members can be detected by the single position detecting means.
As described above, according to the present invention, potentiometers of the same number as that of the driven members can be eliminated. Moreover, the single position detecting means is provided in place of the potentiometers, so that the cost of the driving apparatus can be reduced.
According to another aspect of the present invention, there is provided an air conditioner for a vehicle, including an air conditioning casing for forming an air path, an evaporator disposed in the air path for cooling air, a heater core disposed in the air path for heating the air, an inside air/outside air switching driven member for switching air to be introduced into the air path between an inside air and an outside air, a temperature adjusting driven member for adjusting temperature of the air, an air-blowing mode switching driven member for switching a direction of blowing the air into a vehicle compartment, electric motors for driving the three driven members, control means for controlling operation of each of the electric motors, and a position detecting means for detecting rotation position of each of the electric motors. When a request of simultaneously operating at least two driven members out of the three driven members is received, the control means controls the electric motors so as to sequentially operate the driven members requested to operate one by one.
Thus, according to the air conditioner, in a manner similar to the driving apparatus, no potentiometer is required. Moreover, only one position detecting means is required in place of the potentiometers. Thus, the cost of the driving apparatus in the air conditioner for a vehicle is reduced.